Bleeding/Seams on AO Bake
Looks like you have intersecting or non-manifold geometry and the problem are aliased edges. There is no way to bake the AO with anti-aliased intersecting edges, that is not yet supported.

There are 3 option:


get rid of the intersections (or non-manifold sections)
bake a much much higher resolution and then downscale the texture
go over those edges with paintbrush and fix them manually